Markle's bridal gown work of Givenchy's Clare Waight Keller

LONDON (AP) — Clare Waight Keller of Givenchy is the master British designer behind the sleek silk boat-necked gown and long billowing veil worn by Meghan Markle as she walked down the nave of St. George's Chapel for her wedding to Prince Harry.

The clean lines of the white dress highlighted Markle's smiling face Saturday as she sat at the altar of the chapel, holding Harry's hand as the sprawling train lay at her feet.

"It's brave to not have decorations and embellishments. What a strong fashion statement. It's modern and classic at the same time," Phillipa Lepley, a leading London bridal designer, told The Associated Press. "The overall look is very '50s and gorgeous!"

Waight Keller, the first female artistic director of French fashion house Givenchy, met Markle earlier this year, Kensington Palace said. It said Markle wanted a dress with an "elegant aesthetic, impeccable tailoring, and relaxed demeanor."

The dress featured no lace or embroidery, carrying a classic boat neckline, three-quarter length sleeves and an A-line skirt with a train measuring nearly 6 feet from the waist. Markle complemented it with a tiara, an embroidered cathedral-length veil, a bracelet and a small diamond stud earrings.

"The dress is simply beautiful in its classic simplicity," said Caroline Burstein, owner of Browns Bride, a top London bridal boutique. She called it "a nod to Grace Kelly, Audrey Hepburn and every iconic wedding we have witnessed throughout the 20th and 21st century. It's perfect for her and for the occasion they are celebrating."

The veil carried floral references to all 53 countries in the Commonwealth, the group of countries that roughly corresponds to the former British Empire and is headed by Markle's new grandmother-in-law, Queen Elizabeth II. The palace said workers spent hundreds of hours sewing the delicate flower designs into the veil, meticulously washing their hands every half hour to keep the silk tulle and threads clean.

The palace said, in addition to the Commonwealth flowers, Markle also selected two other plants: Wintersweet and, in a nod to her birthplace, the California poppy.

Markle's choice was no casual affair. Televised royal weddings like this have a massive effect on what brides everywhere want to wear and are closely watched across the fashion industry.

"There are no seams in the bodice," Lepley noted. "Incredibly clean and plain dresses such as this are very time consuming and complicated to make, because unlike a lace dress, there is no room for any errors. You can't hide any wrinkles, as the fabric has to sit perfectly."

Princess Diana's 1981 wedding gown, with its romantic details and dramatic train, defined the 1980s fairytale bridal look. More recently, when Kate Middleton married Prince William in 2011, her long-sleeved lace gown immediately sparked a trend for more covered-up, traditional lace bridal dresses.

As with many royal occasions, every item of clothing was laden with history and meaning.

Markle's tiara was a diamond bandeau made for Queen Mary and specifically designed to accommodate the central brooch, given as a gift to the then-Princess Mary in the late 19th century and passed on to Elizabeth in 1953.

The forget-me-nots in the bridal bouquet were a nod to the late Princess Diana, Harry's mother — they were her favorite flower. The myrtle sprigs packed among them were drawn from a plant grown from myrtle used in Elizabeth's wedding bouquet in 1947. Other flowers were hand-picked by Harry himself from the garden in Kensington Palace.

The designer of Markle's dress was one of the wedding's most closely-guarded secrets, sparking months of speculation.

Waight Keller was a surprise choice — her name was not among the many designers slated to be possible contenders for the dress commission of the year. Educated at the Ravensbourne College of Art in south London, Keller kicked off her career at Calvin Klein in New York designing women's ready-to-wear before moving to Ralph Lauren to work on the men's "Purple Label."

After stints at Gucci, Pringle and Chloe, she was appointed as artistic director of Givenchy haute couture and women's and men's ready-to-wear last year.

Before the wedding, the top guesses from Britain's bookmakers for Markle's wedding dress designer included Erdem, founded by Canadian-born designer Erdem Moralioglu; Ralph & Russo, the couture designers that Markle chose for her engagement dress; Alexander McQueen, the label that created Kate's wedding gown; Stella McCartney; Burberry and Oscar de la Renta.

One of the guesses proved right in the second round. For the Saturday evening reception hosted by Prince Charles, the newly titled Duchess of Sussex wore a bespoke McCartney design: a white silk crepe gown with a high neck, bare shoulders and full skirt.